Earlier this year, Google launched the Android version of its Play Music app, which is intended to compete with stream-on-demand services such as Spotify and Rdio. Today, the Google Play Music software finally lands in the iOS ecosystem, in the form of an app customized for the iPhone.

It's free to download the app, and if you've already purchased tunes from Google Play – or uploaded tracks from your own collection – it'll be free to listen to those songs, too. But to make the most of the software, you'll need an All Access membership, which will set you back 10 bucks a month (on par with similar offerings from streaming music competitors).

For that price, you get unlimited access to millions of tracks, the ability to create and store playlists, and to listen to "custom" radio stations, à la Pandora. But before pulling the trigger, it may be worth reading some side-by-side comparison tests of Google Play Music and Spotify and the rest of the streaming bunch – although the price points are comparable, the same is not always true of the features.

So how does the iOS version of the Google Play Music app hold up? Pretty well, writes Ryan Whitwam of PCMag.com.

The software is "a mostly successful translation of the app to Apple's platform, and it fits in with the new style well," Mr. Whitwam argues. "However, there are a few places where the lack of a back button (as you'd find on Android devices) is a little bit of a pain point. It's also only optimized for the iPhone, so the UI is somewhat awkward on the iPad."

Streaming music services are a big business these days, and the market is only expected to grow. According to market analytics firm Parks Associates, the number of music streaming subscribers worldwide could reach 15 million globally by 2017.